1. Field of the Invention
This invention relates to a nose mask for applying an anesthesia gas to the laboratory animal.
2. Description of the Related Art
Recently, there has been in wide use a method called “in vivo imaging” where an in vivo action in a laboratory animal such as mouse is directly observed as it is alive. For example, after a diseased part such as tumor is created in the laboratory animal, and agents labeled by phosphors and the like is dosed in the laboratory animal through a blood vessel injection, collection or dispersion of the agents with time to and from the diseased part can be observed by projecting an exciting light onto the diseased part.
Further, there exists a method of chemiluminescence where a biological tissue is investigated (gene analysis, disease, aging) or an organic material or a polymer is evaluated using a reaction where light is emitted (chemiluminescence) with the reaction when materials react with each other. In this chemiluminescent method, the chemiluminescence is generated by bringing an organic material into contact with a chemiluminescent substrate after, for example, the organic material is labeled with antigen and an antibody labeled with a labeling material which generates the chemiluminescence when contacting to the chemiluminescent substrate is brought into contact with the antigen.
In the technic of the in vivo imaging, since the fluorescence or the chemiluminescence to be detected is very weak, the laboratory animal which is the object is housed in a casing light-shielding to external light and the fluorescence or the chemiluminescence discharged from the laboratory animal is detected by a cooled CCD. Specifically, in the method of the fluorescence, from an exciting light source provided in the casing, the exciting light is projected onto the laboratory animal and the fluorescence discharged from the laboratory animal is passed through a high-sensitive lens to image on the cooled CCD thereby visualizing the fluorescence. In the method of the chemiluminescence, the chemiluminescence discharged from the laboratory animal is passed through a high-sensitive lens to image on the cooled CCD with the exciting light source kept put off. In either of the method of the fluorescence and the method of the chemiluminescence, an unexpected recovery of the consciousness of the laboratory animal deteriorates the quality of the image taken and accordingly, an anesthesia is applied to the laboratory animal during the experiment. There is disclosed in PCT Japanese Publication No. 2005-517507, a system for applying an anesthesia where an anesthesia gas is mixed in a low-pressure oxygen gas to form an anesthesia gas by the use of a vaporizer and the anesthesia gas is supplied to a nose mask in the casing. The flow of the anesthesia gas at this time is controlled by an on-off valve and the flow of the anesthesia gas upon discharge is controlled by a vacuum pump.
In the technic of the in vivo imaging, it is necessary in order to prevent deterioration of the quality of the image taken due to a recovery of the consciousness of the laboratory animal that the laboratory animal in the casing during an image taking is applied with an anesthesia and accordingly, it is necessary to introduce and discharge the anesthesia gas into and from the nose mask in the casing. Introduction and discharge of the anesthesia gas into and from the nose mask in the casing can result in fear that the anesthesia gas leaked from the nose mask can remain in the casing. When the anesthesia gas remains in the casing can result in fear that the worker inspires the anesthesia gas when taking out the laboratory animal upon end of the image taking.
In the technic disclosed in PCT Japanese Publication No. 2005-517507, when the flow of the anesthesia gas upon discharge is increased by a vacuum pump, thereby reducing the anesthesia gas leaked from the nose mask, it becomes difficult to apply a sufficient anesthesia to the laboratory animal. On the other hand, when the flow of the anesthesia gas controlled by an on-off valve to increase the flow of the supply side, thereby applying a sufficient anesthesia to the laboratory animal, it becomes difficult to prevent the anesthesia gas leaked from the nose mask from remaining in the casing.